refactor(ai): hoist Provider core to shared cmd_chat/ai/ (P1)

Move providers.py + profiles.py from cmd_chat/agent/ to a shared
cmd_chat/ai/ package so the operator bridge and the /ai chat agent can
consume one model-agnostic Provider core (groundwork for harness-mode
operators). Pure refactor — no behaviour change.

- cmd_chat/ai/{providers,profiles}.py: the canonical modules (moved verbatim)
- cmd_chat/ai/__init__.py: re-exports the public API
- cmd_chat/agent/{providers,profiles}.py: thin back-compat shims re-exporting
  from cmd_chat.ai (keeps `from cmd_chat.agent.providers import …` working,
  e.g. hh/scripts/bench-native-harness.py)
- internal agent consumers (memory/bridge/__main__/__init__) point at cmd_chat.ai

125 tests pass; shim identity verified (re-exports are the same objects).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd_chat/ai/__init__.py

@@ -0,0 +1,37 @@
+"""Shared model-agnostic AI core for hack-house.
+
+Houses the provider abstraction (``providers``) and named model profiles
+(``profiles``) consumed by BOTH the in-room ``/ai`` chat agent and the operator
+bridge. Hoisted here from ``cmd_chat.agent`` so the operator can run any
+function-calling model as an operator, not just Claude. The old
+``cmd_chat.agent.{providers,profiles}`` paths remain as thin re-export shims for
+backward compatibility.
+"""
+
+from .providers import (
+    Msg,
+    OllamaEmbedder,
+    OllamaProvider,
+    Provider,
+    ToolsUnsupported,
+    make_provider,
+    preflight,
+)
+from .profiles import (
+    find_profiles_file,
+    load_profiles,
+    provider_from_profile,
+)
+
+__all__ = [
+    "Msg",
+    "Provider",
+    "ToolsUnsupported",
+    "OllamaProvider",
+    "OllamaEmbedder",
+    "make_provider",
+    "preflight",
+    "load_profiles",
+    "find_profiles_file",
+    "provider_from_profile",
+]